Chemical Geology, Nov 25, 2012, Vol.332-333, p.116(8)
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.chemgeo.2012.09.046 Byline: Thilo Rennert, Karin Eusterhues, Vincent De Andrade, Kai U. Totsche Keywords: Geogenic CO.sub.2; Soil formation; Fe speciation; Green rust; Organic complexation Abstract: Geogenic CO.sub.2, which ascends on so-called mofette sites, may affect development and properties of soils. Therefore, we studied soils on a mofette site in the Czech Republic at three spots differing in the partial pressures of soil CO.sub.2 (p(CO.sub.2)=0.04, 1, and 1). We recorded 69 Fe K-XANES spectra in 5 regions of interest on 3 thin sections in fluorescence mode. Iron was enriched in filled pores, e.g., former root channels. Generally, most of the Fe was identified in different clay minerals (smectites, illites and chlorites). Minor pedogenic Fe contributors were ferrihydrite, green rust, magnetite, maghemite, vivianite and siderite, whereas typical soil Fe (hydr)oxides such as goethite, hematite or lepidocrocite were never doubtlessly identified. The Fe(II)-containing minerals were particularly detected at p(CO.sub.2)=1 indicating an effect of soil CO.sub.2 on the formation of secondary Fe phases. Organic Fe complexes were less important, and their formation seemed to be inhibited at p(CO.sub.2)=1. We thus conclude that geogenic CO.sub.2 affects pedogenesis and causes quantitative and qualitative variations of Fe speciation. Article History: Received 11 July 2012; Revised 26 September 2012; Accepted 27 September 2012 Article Note: (miscellaneous) Editor: Dr. J. Fein
Iron (Metal) ; Smectite ; Iron Oxides ; Soils ; Chlorites (Minerals) ; Iron Ores
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